36 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



and the intestine is now seen to be completely separated 

 off from the pyloric sac, while the csecal extremity of a 

 new tube — a diverticulmn rmniing posteriorly and to the 

 left from the rectmn is seen in the middle line between 

 the stomach and the intestine. In the next section 

 figured (PL II. fig. 4), which is just ten further forward, 

 this diverticulum is seen as a large distinct tube lying 

 near the centre of the body and between stomach and 

 intestine. It can be traced alongside the latter (see PI. 

 II. fig. 5) for about 20 sections when (PL II. fig. 6) the two 

 tubes communicate, and finally after another 20 sections 

 the two have completely coalesced to form a single medio- 

 ventral tube, the rectum. PL II. fig. 6 (section 134) shows 

 the two tubes communicating by a narrow passage pro- 

 vided with long cilia; PL 11. fig. 7 (section 151) shows the 

 tubes almost completely joined there being only a small 

 chink left to represent the intestine, the greater part of 

 the lumen being derived from the diverticulum ; finally 

 PL III. fig. 1 (section 155) shows the median rectum, still 

 a little unsymmetrical in shape. It results from this 

 arrangement seen in the last 50 sections that there must 

 be only a very narrow slit-like opening from the intestine 

 into the point of junction of the rectum and its CEecum. 



These sections (103 to 155) show also the gradual but 

 marked growth of the pharynx in size and differentiation 

 as it is traced forwards. Figures 4 and 5 on PL II. and 

 fig. 1 on PL III. show the triangular shape, the broad 

 ventral base, the thin lateral walls, and the formation of 

 ciliated tracts dor sally and ventrally, the dorsal being a 

 pair of prominent pads which bound the epipharyngeal 

 groove (see PL 11. fig. 5, ep.p.), while the ventral is a flat 

 hypopharyngeal plate (hy.p.) which can be traced forwards 

 to near the endostyle. Section 113 (PL 11. fig 4) shows 

 the anterior bifurcation of the testis (sjj.) which dies out 



